A relatively new type of a power semiconductor device includes a conventional MOSFET (metal oxide semiconductor field effect transistor) topology with a source region, a drain region, a body region, a drift region, a gate electrode and a gate dielectric, and further includes a drift control region and a drift control region dielectric between the drift region and the drift control region. The semiconductor device can be switched in an on-state or an off-state by applying a suitable drive potential to the gate electrode.
In operation of the semiconductor device the drift control region is connected to a biasing source that, when the semiconductor device is in an on-state, biases the drift control region such that a conducting channel is generated in the drift region along the drift control region dielectric. This conducting channel is an inversion channel or an accumulation channel, namely dependent on the doping type of the drift region, and helps to reduce the on-resistance of the semiconductor device.
In the off-state of the semiconductor device, a space charge region (depletion region) expands in the drift region and the drift control region. When the semiconductor device is switched from the off-state to the on-state, this depletion region has to be removed from the drift region.
There is a need to provide a semiconductor device with a drift region and a drift control region that is capable of switching fast from the off-state to the on-state and that has low losses during the transition from the off-state to the on-state.